1. Field of the Invention
One embodiment of the present invention relates to a semiconductor device.
Note that one embodiment of the present invention is not limited to the above technical field. The technical field of one embodiment of the invention disclosed in this specification and the like relates to an object, a method, or a manufacturing method. One embodiment of the present invention relates to a process, a machine, manufacture, or a composition of matter. Specifically, examples of the technical field of one embodiment of the present invention disclosed in this specification include a semiconductor device, a display device, a liquid crystal display device, a light-emitting device, a lighting device, a power storage device, a memory device, an imaging device, a method for operating any of them, and a method for manufacturing any of them.
In this specification and the like, a semiconductor device generally means a device that can function by utilizing semiconductor characteristics. A transistor and a semiconductor circuit are embodiments of semiconductor devices. In some cases, a memory device, a display device, an imaging device, or an electronic device includes a semiconductor device.
2. Description of the Related Art
A voltage controlled oscillator (VCO) is one of oscillator circuits and is capable of controlling the oscillation frequency of an output signal by signal voltage to be supplied. A ring oscillator VCO is known as an example and disclosed in Patent Document 1.
A voltage controlled oscillator is used in a phase-locked loop (PLL) or a DC-DC converter. A PLL is used, as a circuit for generating stable frequency signals, for a central processing unit (CPU), a programmable logic device, or the like.